its flexibility. While several other brain regions rely on experience to estimate values, vmPFC can encode values that must be computed quickly, often just prior to or during an action.86 The shell receives the densest innervation from the vmPFC and from the agranular insular cortex, areas involved in monitoring the internal milieu. vmPFC projections also extend dorsally into the medial wall of the caudate nucleus.81 Nonetheless, the vmPFC projection field to the striatum is the most limited of the frontal cortex and is concentrated within the shell and a narrow column along the medial border of the caudate nucleus adjacent to the ventricle (Figure 4a).
